Studies summarized in the progress report to define the genetic and possible viral basis of the disease will continue during the coming year. Also under way are studies to define the immune studies of the "BB" rats with regard to cellular and humoral mechanisms which might play a role in their diabetes. The immune status of the diabetic rats is being studied by means of in vitro response of their lymphocytes in MLR and antibody producing capacity. More transplantation studies are planned. The results of vascularized pancreas transplants will be compared to those obtained with transplanted isolated islets.